Torque indicating wrench



y 7, 1942- A. BRUNELLE TORQUE INDICATING WRENCH Filed Sept. 2, 1939INVENTOR flwwrBRz/Mzm 5' ATTORNEY Patented July 7, 1942 UNlTEDf STATESPATENT OFFICE bRQUE lNli l' l iiliG WRENCH V August-:Brunelle,Ridgewood, N. J., assignor to :WrightAei-onautical Corporation,acorporation r of I New York Application September 2, 1939, Serial No.293,222

-Claims.

This'inventionrelatesito wrenches of the type which are capableofregistering'the torque applied-thereby and a particular object is toprovide means by which the application of a preset torque is indicatedto the operator through his tactile sense, rat-her than-requiring hisvisual observation of meters or dials according to conventionalpractice. By the use of a tactile indicator, no limitation is imposed onproper torque measurement due'to lighting conditions or accessibility ofthe parts being worked upon, and indication willdefinitelybeconveyed tothe operator without undue concentration by him-onjust one phase of thewrench operation, thus allowing for more expeditious work with increasedaccuracy. A furtherobject is to provide'means in a torque indicatingwrench :byv which; the nut or other part being worked uponwill be firmlyseated'atthe desired torque by application of vibrating forces thereto,such vibration being applied only at the desired torque whereby fatigueof. the operator is minimized. Still another object is to provide atorque metering wrench of. rugged and simple designwhich will beadaptable to use over a large range of boltandnut sizes. i In general,torque. metering 1 or indicatin wrenches are usefulin the automotive andaircraft arts, and in others, where mechanisms are highly developed andwhere it is desired to develop the strength-of screw connections to thefullest extent. It is well known that loose screw connections aresubject to failure and further loosening in machine assemblies, whiletoo tight screw connections cause overstressing and failure ofmaterials. Each screw size has an optimum tightness which is difiicultof attainment-without an adequate torque metering wrench This inventionprovides a wrench which is as easy to use as an ordinary wrench, andwhich is reasonable in cost.

Additional objects of the invention will become apparent in reading thesubjoined detailed description in connection with the drawing, in whichFig. 1 is a plan of the wrench;

Fig. 2 is a longitudinal section on the line 22 of Fig. 1; r

Fig. 3 is a section on the line 3-3 of Fig. 2;

Fig. 4 is a longitudinal section through part of the wrench on a planenormal to that on which Fig. 2 is taken, and

Fig. 5 is an enlarged section on the line 55 I of Fig. 4.

The wrench comprises an end terminal [0 provided with a squared portionH over which the components of socket wrench sets may be assembled,the'terminal'having a transverse hole in which a torque bar I 2 isinserted, the latter being retained in the terminal by suitable meanssuch as a set screw I 3; The bar is preferably of spring steel, and maybe any shape or of uniformsection throughout its length. Onthe free endof the bar, a handle I4 is secured, the handle coinprising a hollow, asat I5, and a knurled grip IS, the handle-being slipped over the bar andpinned as at H. A strip or plate l8, having substantial stiffness in theplane of action of the wrench, issecured to the terminal It by a screwIB'a'nd pins 20, the latter securing the strip and terminal againstrelative rotation. At the free end of the strip I8, 2. laterallyextended portion 2| is provided, the substantially arcuate edge 22 ofwhich is calibrated to show applied torque. A guide 24, clamped to thebar l2, carries an adjustable grooved screw element 25 engaged over theedge of the portion 2| to prevent vertical displacement of the strip,and to adjust the contact points later described, this element alsoserving as an index against which the scale marks on the strip may beobserved.

The portion 2!, is formed with a substantially arcuate slot 2'! throughwhich a pin 28 passes, the pin having fiat sides to prevent turning inthe slot, having a contactpoint at its lower end 'of a diameterappropriate to embrace the torque tolerance permitted in operating onbolts or nuts, and having screw threads at its upper end. A nut 29 overan index tab 29 serves to secure the pin at any selected position alongthe slot 21. A second contact point 30 is clamped around the bar 12,insulated therefrom by a strip 3|, the contacts 30 and 28 beingengageable on torque application and bending of the bar 12 to close anelectric circuit formed through the strip and bar and through a wire 32leading into the handle hollow [5 through appropriate drillings thereinand in the element 24.

Within the handle is secured a ferrous core 34 by screws 35, a springarmature 36 being secured between the core and handle and extendingaround the handle bore in clearance relation to carry apole piece 31 anda tapping button 38. Solenoid windings 39 around the core 34 connect tothe wire 32 and to one prong 40 secured in an insulating plate 4l'adjacent the handle end, another prong 42 therein being connected to thebar l2 by a wire 43.

Preferably the solenoid is energized by low voltage alternating currentthrough a transformer operating from a conventional lighting circuit,low voltage being used to avoid possibility of shocks to the operator.Alternately, the solenoid may be arranged as a buzzer operating on lowvoltage direct current, the tapping button comprising a make-and-breakcontact.

If the device be adapted for higher voltage, the wiring would preferablybe insulated, in which case the bar lZ-would comprise 'a tubethroughwhich wireflapasses to the terminal I and thence along the strip18 to the contact 28 which would be insulated from the wrench proper.

The tapping button is preferably, active in the 1 plane of action of thewrench. In operation the operator pulls upon the handle-all:and'ishortlycontacts 28 and 30 engage.to energize-the:sole i' noid34-49, vibrating the handle to apprise the operator that the desiredtorque'hasbeenapplied.

The vibration imposed upon the wrench during "slottoward the handle end,an adjustable consaid contacts, and a vibrating armature actuated bysaid solenoid when energized, said armature having an element fortapping contact with the handle to apprise the operator thatpredetermined torque has been applied.

3. A torque metering wrench comprising an elastic bar of uniform crosssection, a terminal element embracing one end of the ba.r and securedthereto, a handle embracing and secured to the other end of the bar, arelatively rigid strip initially parallel to the bar and secured to saidterminalelement, said strip having an arcuate tact element.movable alongsaid slot, a fixed f contactelement secured to the bar and engageablewith'the'adjustable contact upon bar bending,asolenoidin said handle incircuit with said application of torque within the deflection rangeembraced by the contacts 28, 30 also serves to vibratethe nut or boltworked upon into a firm seat with its coactingmachine parts.

While I havedescribed myinvention in detail inits' present'preferredembodiment, it will be obvious tothose skilled, in the art, afterunderstanding my invention, that various changes and modifications. maybe made therein without departing from the spiritfor scope thereof. Iaimin the appended claimsi to. cover 'alli'such modiiications and changes.U I

Ic'laim;"

'1, A torque metering wrench comprising an elastic bar of uniform crosssection,; a terminal= element embracing one end of the bar and securedthereto, a handle. embracing and, secured to the other end of ,the bar arelatively rigidstrip initially para'u m the b r, and secured -to saidterminal element, said strip having an arc u-- ate slot toward thehandle end, an adjustable contact element movable along said slot, afixed contact element secured to the bar and engageable with theadjustable contactupon bar bending, an electric, vibratorin said handlein circuit with said'contacts, and an electric power supply:

pluginthe handle end., i

2. A torque metering, wrench comprising anelastic bar ofuniform crosssection, a terminal contacts, and a vibrating armature actuated by saidsolenoid when energized, said armature having an element for tappingcontact with the handle] to apprise the operator that predetermined'torque has been applied, said tapping armature being .so oriented inthe handle as to apply'a vibrating force in the, planeof action or thewrench to assist in seating nuts or other devicesto which torque isapplied.

4.,iAftorquemetering wrench including-an operating handle and-elementsrelatively movable in proportion to the torque applied, a vibrator incured to the guideway, another contactor on the element embracing oneend of the bar and -secured thereto a handle embracing and secured tothe other end of the-bar, arelatively. rigid strip initially parallel tothe bar and secured to 1 said terminalelement, said-strip having anarcuate slot toward the handle end,- an adjustable contact element.movable along said slot but securable at a desired position to thestrip, a fixed contact element secured to -the bar and engageable withthe adjustable contact ,upon bar bending, a solenoid in saidnhandle incircuit with other member, said-contactors being engageable overaselected narrow range of deflection as one member is deflected relativeto the other upon torque application to the elastic member, saidcontactors being disengaged from one another upon torqueapplication lessthan or greater than that necessary to cause the contactors to meet insaid narrow range oideflection, electric signalling means actuated byengagement of said contacts,janda hollow handle on the end of theelastic member within which said signalling means is-disposed.

a AUGUST BRUNELLE.

